I have a 50HP johnson 1999. I am having issues getting the motor to start. It won't start at idle, but will when I open the throttle a little. Once started I close the throttle and try to idle, but craps out around 1500rpm and below.

I checked the compression on both cylinders. Top cylinder was ~125psi and bottom was ~140-145psi.

I have recently replaced the fuel pump which was not working and also rebuilt and cleaned the carbs thoroughly. I don't think anything is wrong with the idle path in carbs, but could be wrong.

Could I have a timing issue at idle or maybe something wrong with reed valves? Are there any tests that I could perform to check the reeds? I also read about a one way check valve for fuel recirculation. Could this have failed? Does anyone know where this is on this engine (intake manifold or bottom of crankcase by shaft)?

Any suggestions would be appreciated.